3.3 threats to biodiversity. 1.habitat loss (most significant threat to biodiversity) occurs when...

3.3 Threats to Biodiversity

1. Habitat Loss (most significant threat to biodiversity)Occurs when events alter an ecosystem so much that many species can no longer survive there.

• a) Deforestation• Occurs when forests

are logged or cleared for human use and are not replanted.

• (see video clip)http://hernadi-key.blogspot.com/2008/12/global-warming-aided-by-drought.html

• b) Draining Wetlands• Often drained for farming, construction or

mosquito control.• *Note 90% of wetlands along lake Ontario have been

destroyed.

http://www.corbisimages.com/stock-photo/rights-managed/AY001968/watermelon-patch-on-drained-wetlands

2. Alien Invasive Species(2nd largest threat to biodiversity)

• Species introduced to new parts of the biosphere from other regions;

• May be introduced on purpose or accidentally in shipments of food or goods.

• They take over the habitat of native species.

• Arrive, Survive and Thrive.

• Examples: • i) European Earwig• ii) Giant Hogweed. • https://www.youtube.com/watch

?v=rPeg1tbBt0A

• http://humberetc.com/2011/04/13/giant-hogweed-can-cause-burns-blindness/http://humberetc.com/2011/04/13/giant-hogweed-can-cause-burns-blindness/

• Zebra Mussels• Native to Asia;

introduced to the Great lakes through ballast water in the 1980’s

• Out-competes native mussels and other organisms that share the same food; impacts other levels in the food chain.

• (Show Video clip)

http://en.wikipedia.org/wiki/File:Zebra_mussel_infestation_Ormond_Lock.jpg

http://en.wikipedia.org/wiki/File:Zebra_mussel_GLERL_3.jpg

• Round Gobies: • Introduced by ballast water in late 80’s.• Competes with native fish for spawning areas• Eat many aquatic species which affects food chains of native

species.

• 10 years after arrival, found in all 5 great lakes.• Lake Erie population in the billions.

http://www.dnr.state.oh.us/Default.aspx?tabid=22723

3. Overexploitation

• Use or extraction of a resource until it is depleted

• e.g.: over fishing of Atlantic cod

• Hunting of the passenger pigeon.

http://en.wikipedia.org/wiki/File:Surexploitation_morue_surp%C3%AAcheEn.jpg

4. Disrupting Connectivity Across Ecosystems

• When one species is affected in an ecosystem, other ecosystems may be impacted.

• e.g. Salmon populations may be connected to the health of temperate rainforests in B.C.

http://www.jrmartinmedia.com/2011/07

5. Extinction• The death of all the individuals

of a species• e.g. dinosaurs• May happen through:a) Background Extinction:• Caused by slow change to

ecosystem over time.

b) Mass Extinction:• occurs quickly• may be caused by humans

(e.g.overexploitation) or • by natural causes (e.g.

meteorite)• Current extinction rates are 100-

1000x higher than the background extinction rate.

http://www.dailymail.co.uk/news/article-1270679/Scientists-step-closer-bring-mammoth-dead.html

Species currently endangered• Glass frog (central

and south america)

• Chinese giant salamander

http://www.allpics4u.com/nature/strange-and-exotic-endangered-species.html

• Frigate Island Beetle

• Giant Coconut Crab (Guam and Pacific Islands)

http://www.allpics4u.com/nature/strange-and-exotic-endangered-species.html

Canadian Endangered Species

• Beluga whales• American Bison• Cougar• Black-footed ferret• Northern Fur Seal• Wolverine• Marmot• +many more

………. http://www.photosshow.com/beluga-whale/